The award-winning MHP30-36 from TE Circuit
Protection is a metal hybrid polymeric positive temperature
coefficient (PPTC) device that combines a bimetal protector in
parallel with a PPTC device. It offers 30-A hold current and an
initial resistance of less than 2 mΩ, and provides
resettable overcurrent and over-temperature protection. The company
saw a need for the PPTC for Li-ion technology especially because
Li-ion requires a higher level of circuit protection since it has a
higher power level than NiCd and lead-acid technologies. The
company also saw that there were limited battery protection options
available on the market at ratings above 30-A hold current and 30
Vdc.

The device combines a bimetal protector and a
PolySwitch PPTC device. This combination incorporates the best
features of a bimetal breaker and PPTC and allows the PPTC
technology to be used in higher current applications. The MHP
device can be useful in dc-rated designs that require
arc-suppressed, latched, high-current protection. The resettable
MHP30-36 device provides excellent arc suppression characteristics
compared to standard breaker devices that must limit the number of
switching cycles since arcing between contacts may damage them. It
can be used for portable or motive applications including cordless
power tools, medical devices and e-bikes.

The design team had six members and 11 key
contributors who needed about three years to develop the
award-winning technology and it certainly wasn’t without
its challenges. The team had to come up with a method to achieve
proper contact balance for the double make/ double break design.
Additionally, because every battery pack design is custom-made and
the protection requirements vary by end customer and application,
optimizing the device specifications to cover a broad number of end
customer requirements, was a challenge. Customer interest in the
core MHP technology has led to some extensions of the technology to
create three-terminal MHP devices that enable external electronic
activation of the device via a signal line.